Normal boys enter puberty at the age of 10-13 and begin to develop secondary sexual characteristics, but the timing of the onset of development can vary from boy to boy depending on individual differences. Development in boys mainly refers to the development of secondary sexual characteristics. In general, boys who develop secondary sexual characteristics before the age of 10 should be suspected of having precocious puberty, which may affect the overall development of the child, and thus the final height. It is normal for boys to start developing secondary sexual characteristics between the ages of 10 and 13, with the main manifestations including the maturation of sexual organs, changes in voice, the appearance of throat nodes, and so on. However, it should be noted that boys usually start to develop no later than 14 years old. If they do not develop by the age of 14, it means that they may have developmental delays and need to be examined by the pediatrician in a timely manner. In short, boys who develop too early or too late are not good for their health. Parents need to pay attention to their children’s growth and development in daily life, and pay attention to balanced nutrition and reasonable diet.